March 15, 2013

M81 (March 11 & 12, 2013)

M81 is roughly 12 million light years away.  We see it in the constellation Ursa Major.  In fact, it sits just west of the Big Dipper's bowl.  M81 is the largest of a group of nearby galaxies called, with affection, the M81 group.  The galaxy just below (west of) M81 in the image is PGC 28757 or Holmberg IX, an irregular dwarf satellite galaxy of M81.  There are other, more distant galaxies in the image, too, but I have no idea what names they carry, or if they do.

This image was taken from skies darker than my normal location.   Distant galaxies are always better seen from darker skies.  The image is shrunken slightly for noise reduction.

If you look closely at the image above, you will see there are clouds to the left of M81 running from the top to the bottom of the image.  These are probably clouds of gas and dust within our own galaxy and have earned the name "Galactic Cirrus."  See here and here.  These clouds are very dimly lit.  They are more easily seen in this inverted version:


Telescope: Astro-Tech AT111EDT and William Optics AFR-IV (eff. at f/5.6)
Camera and Exposure: SXVF-H9 (29x900"), Alnitak Flat-man flats
Filter: Astronomik CLS
Guiding: SX Lodestar and SX OAG
Mount: Takahashi NJP
Software: Nebulosity, Maxim DL, Photoshop CS3
Location: SHSU Observatory near Huntsville, TX; Starry Nights Bed and Breakfast near Wimberley, TX

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